This invention covers a circuit arrangement for the generation of stepping pulses for the acceleration of a stepper motor where a pulse generator is employed which generates command pulses which are coordinated to the stepping pulses. An amplifier is employed which has at its input the stepping pulses and which outputs to the stepper motor the voltages corresponding to the stepping pulses.
According to a publication "Celerate the Digital Stepping Motor" Electronic Design 1, Jan. 4, 1973 pages 84 to 87, there is already known a circuit arrangement for the generation of stepping pulses for the drive of a stepper motor. This circuit arrangement consists of a multiplexer or frequency divider having an input which receives command pulses of a predetermined repetition rate and which generates at its output the stepping pulses. The repetition rate of the stepping pulses is equal to the product of a factor which customarily is smaller than one and the repetition rate of the command pulses. This factor is determined by data words which are fed to the multiplexer. The circuit arrangement furthermore contains a counter which can be counted up or down by means of counting pulses of predetermined repetition rate. The counter generates at its output the data words. During acceleration of the stepper motor, the counter is counting up starting with an initial counter position to a final counter position by means of counting pulses which have a repetition rate considerably smaller than the rate of the command pulses. Depending on the appropriate counter position of the counter stage, the repetition rate of the stepping pulses constantly increases due to the changing values of the data words. At the moment the counter stage reaches its final counter position, further counting is inhibited and the repetition rate of the stepping pulses is not changed any further. During deceleration of the stepper motor the counter stage is again counted downwards by means of the counter pulses. In corresponding fashion to the acceleration of the stepper motor, the repetition rate of the stepping pulses is reduced in dependence upon the respective counter position. In this known circuit arrangement the repetition rate of the stepping pulses can be adjusted such that it can be changed during acceleration and during deceleration of the stepper motor linearly, logarithmically, or exponentially. The stepper motor is, however, in this mode not operated at its optimum load angle range. In the case where stepper motors are used as drives for positioning, it is, however, frequently necessary that the time required to reach a particular position be kept at a minimum. This positioning time is shorter the higher the torque of the stepper motor. The torque is not only dependent upon the properties of the stepper motor but also on the mode of operation.
The above described counter and multiplexer of the Electronic Design I article are similar to the counter ZS and multiplexer FT of FIG. 4 discussed below.